1. Field of the Invention
The present invention relates to a method and an apparatus by which iron core pieces are punched or blanked by press working a material (for instance, a thin metal sheet) and the blanked iron core pieces are laminated to manufacture a laminated iron core.
2. Description of the Related Art
For instance, as disclosed in JP-A-63-228945, a thin metal sheet is sequentially fed to a die apparatus having a plurality of working stations to carry out a blanking or stamping work (a punching work) respectively in the working stations and iron core pieces are blanked or stamped out, dropped into and laminated in the die in a final station.
As shown in FIG. 8A, when caulking parts are formed in the laminated iron core pieces 70 and 71, in the first iron core piece 70 located in a bottom, a caulking through hole 72 is formed. In the iron core pieces 71 after the first iron core piece 70, V shaped caulking parts 73 are formed. A caulking protrusion 74 of the V shaped caulking part 73 is prevented from protruding from a back surface of a laminated iron core 75.
The caulking through hole 72 and the V shaped caulking part 73 are located at the same positions of the iron core pieces 70 and 71 in plan view. As shown in FIG. 8B, a slide plate 78 is provided above a punch 77 which can move upward and downward to carry out a selectively-actuated punching operation that the slide plate 78 is horizontally moved to selectively blank or stamp a material (the iron core piece 70) by the punch 77. FIG. 8B shows a stripper plate 79, a guide member 80 of the slide plate 78, and an upper die 81.